Implement a SHA-256 routine

c/sha256.c

@@ -0,0 +1,153 @@
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static uint64_t pad_length(uint64_t len) {
+  uint64_t space_needed = 1;
+
+  while(((len + space_needed) % 64) != 56) {
+    space_needed += 1;
+  }
+    
+  return space_needed;
+}
+
+static uint32_t rotate(uint8_t bits, uint32_t word) {
+  return (word >> bits) | (word << (32 - bits));
+}
+
+unsigned char *sha2(const char *msg, uint64_t len) {
+  uint64_t L = len * CHAR_BIT;
+  uint64_t needed = pad_length(len);
+  unsigned char *buf = malloc(len + needed + 8);
+
+  if(buf == NULL) {
+    return NULL;
+  }
+
+  strncpy((char *) buf, msg, len);
+  buf[len++] = 0x80;
+
+  for(; needed > 1; --needed) {
+    buf[len++] = 0x00;
+  }
+
+  uint8_t count = 8;
+
+  while(count--) {
+    buf[len++] = (L & ((uint64_t) 0xFF << 56)) >> 56;
+    L = L << 8;
+  }
+
+  uint32_t H[] = {
+    0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
+    0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
+  };
+
+  uint32_t k[] = {
+    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
+    0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
+    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+    0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
+    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
+    0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
+    0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
+    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
+    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
+    0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
+    0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
+    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
+  };
+
+  uint64_t chunk = 0;
+
+  for(; chunk < len; chunk += 64) {
+    uint32_t w[64] = { 0 };
+    uint8_t i = 0;
+
+    for(; i < 16; i++) {
+      w[i] = buf[chunk + (i * 4)] << 24;
+      w[i] |= buf[chunk + (i * 4 + 1)] << 16;
+      w[i] |= buf[chunk + (i * 4 + 2)] << 8;
+      w[i] |= buf[chunk + (i * 4 + 3)];
+    }
+
+    for(i = 16; i < 64; i++) {
+      uint32_t s0 = rotate(7, w[i - 15]) ^ rotate(18, w[i - 15]) ^ (w[i - 15] >> 3);
+      uint32_t s1 = rotate(17, w[i - 2]) ^ rotate(19, w[i - 2]) ^ (w[i - 2] >> 10);
+      w[i] = w[i - 16] + s0 + w[i - 7] + s1;
+    }
+
+    uint32_t a = H[0];
+    uint32_t b = H[1];
+    uint32_t c = H[2];
+    uint32_t d = H[3];
+    uint32_t e = H[4];
+    uint32_t f = H[5];
+    uint32_t g = H[6];
+    uint32_t h = H[7];
+
+    for(i = 0; i < 64; i++) {
+      uint32_t S1 = rotate(6, e) ^ rotate(11, e) ^ rotate(25, e);
+      uint32_t ch = (e & f) ^ ((~e) & g);
+      uint32_t temp1 = h + S1 + ch + k[i] + w[i];
+      uint32_t S0 = rotate(2, a) ^ rotate(13, a) ^ rotate(22, a);
+      uint32_t maj = (a & b) ^ (a & c) ^ (b & c);
+      uint32_t temp2 = S0 + maj;
+
+      h = g;
+      g = f;
+      f = e;
+      e = d + temp1;
+      d = c;
+      c = b;
+      b = a;
+      a = temp1 + temp2;
+    }
+
+    H[0] += a;
+    H[1] += b;
+    H[2] += c;
+    H[3] += d;
+    H[4] += e;
+    H[5] += f;
+    H[6] += g;
+    H[7] += h;
+  }
+
+  unsigned char *digest = malloc(32);
+
+  if(digest == NULL) {
+    return NULL;
+  }
+
+  for(count = 0; count < 8; count++) {
+    digest[count * 4] = H[count] >> 24;
+    digest[(count * 4) + 1] = (H[count] >> 16) & 0xFF;
+    digest[(count * 4) + 2] = (H[count] >> 8) & 0xFF;
+    digest[(count * 4) + 3] = H[count] & 0xFF;
+  }
+
+  return digest;
+}
+
+int main(int argc, char **argv) {
+  for(++argv; argc > 1; ++argv, --argc) {
+    unsigned char *hash = sha2(*argv, strlen(*argv));
+    uint8_t count = 0;
+
+    for(; count < 32; ++count) {
+      printf("%02X", (unsigned) hash[count]);
+    }
+
+    printf("\n");
+  }
+
+  return 0;
+}